Conventionally, solid-state image sensing devices such as CMOS (Complementary Metal Oxide Semiconductor) image sensor or CCD (Charge Coupled Device) are widely used in digital still cameras, digital video camera, or the like.
Furthermore, in recent years, a solid-state image sensing device is packaged in mobile devices such as mobile phone devices having an imaging function.
Of solid-state image sensing devices, a CMOS image sensor is often adopted in a mobile device in terms of a low power supply voltage and a low power consumption.
In such CMOS image sensor, as light enters a light-receiving face of each of pixels which are arrayed in a matrix form, the light is photoelectrically converted into electrical power by a photodiode (PD: Photodiode) that serves as a photoelectric converter provided on each pixel.
The electrical charge that is generated in the PD is transferred through a transfer transistor to a floating diffusion (FD: Floating Diffusion) that is a floating diffusion region.
Thereafter, a pixel signal having a level according to the electrical charge accumulated in the FD is output by an amplification transistor.
Additionally, in the case of a full color solid-state image sensing device, the device has a pixel array in which pixels emitting colored lights of respective red (R), green (G), and blue (B) are arrayed on a plane.
In a lot of cases, a bayer array is adopted as the above-described pixel array.
Absorbing color filters which correspond to the colored lights of the respective red, green, and blue are arranged on the pixel array, and each colored light is selectively transmitted therethrough.
A solid-state imaging device is proposed in which green, blue, and red of photoelectric conversion layers are stacked in layers in the same pixel and in the depth direction thereof.
This solid-state imaging device includes a constitution in which a blue PD (photoelectric converter) and a red PD (photoelectric converter) are formed in a silicon substrate and in the depth direction thereof, and a green organic photoelectric converter that includes electrodes sandwiching an organic photoelectric conversion layer is formed on an upper layer surface of the silicon substrate which is close to a light-receiving face.
According to this structure, the effects, that since an optical loss in the above-mentioned color filter does not occur, the sensitivity thereof is improved, and since a process of interpolating pixels is not carried out, a false color does not occur, can be expected.
On the other hand, as a backside illumination CMOS image sensor, a solid-state imaging device that includes a color filter, a PD that is stacked in a depth direction, and an organic photoelectric conversion layer is proposed.
In the solid-state imaging device, yellow and cyanogen color filters are arranged with a checkerboard pattern, red and blue PDs are arranged to correspond to the respective color filters.
Furthermore, an organic photoelectric converter is disposed on the upper layer of each PD.
The solid-state imaging device is configured to extract a green signal from the organic photoelectric converter, to extract a red signal from the PD located under the yellow filter, and to extract a blue signal from the PD located under the cyan filter.
However, the blue PD and the red PD are stacked in layers in the silicon substrate in the depth direction thereof in the aforementioned solid-state imaging device, and the solid-state imaging device utilizes the principle of diffracting blue light and red light such that an absorption factor of a silicon substrate has chromatic dispersion characteristics.
Particularly, a silicon substrate has the characteristics such that, the shorter the wavelength of light, it is easy for the light to be easily absorbed.
In this case, blue light is completely absorbed by photoelectric conversion at a shallow region which is close to a surface of the silicon substrate which is close to the light-receiving face.
On the other hand, red light only propagates to a deeper region which is far from the light-receiving face side.
Consequently, in the above-described stacked solid-state imaging device, diffraction of blue light and red light is carried out by arranging the blue PD at the shallow region which is close to the surface of the silicon substrate and is close to the light-receiving face and by arranging the red PD at the deeper region which is far from the light-receiving face.
Furthermore, in the case of the stacked solid-state imaging device, in order to sufficiently lower an amount of blue light (hereinbelow, referred to as blue color mixture) that is photoelectrically converted into power at the red PD, it is necessary for a distance between the blue PD and the red PD in the depth direction to be significantly large.